GB/T 4197-1984 Test method for grain size of sintered billets and bars of tungsten, molybdenum and their alloys GB/T4197-1984 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Method for measuring the average grain size of sintered bar and rod of tungsten, molybdenum and alloys This method is applicable to the determination of the grain size of sintered bars and rods of tungsten, molybdenum and alloys. 1 Definition
UDC669.27+669
.28-422:620
GB4197-84
Grain size refers to the scale of the grain size in the organization of metal and its alloy materials. The grain size is expressed by the number of grains per unit area, or by the intercept of each grain.
2 Instruments, equipment, tools and materials
2.1 Horizontal or vertical metallographic microscope
2.2 A grinding machine
2.3 Metallographic sandpaper
2.4 Reagents:
Sodium hydroxide (chemically pure)
Potassium ferrocyanide (chemically pure)
Sulfuric acid (chemically pure)
Anhydrous ethanol, methanol
Beaker, canvas, woolen cloth, silk, chromium oxide or aluminum oxide polishing powder2.6
A set of electrolytic polishing equipment
A mechanical polishing machine
3 Sample preparation
The vertical melting rod should be sampled at the upper standard scale line. For rods, avoid sampling the end with low temperature change. 3.2
Grind the cross section of the sample on the grinding machine. 3.3 According to the method of metallographic grinding, grind on 280~03* sandpaper in sequence. If mechanical polishing is used, grind to 06* sandpaper. 3.4 Polishing:
3.4.1 Electrolytic polishing: The electrolytic polishing liquid for tungsten products is recommended to use 1%~5% sodium hydroxide aqueous solution. The electrolytic polishing liquid for molybdenum products is recommended to use 20%~30% sulfuric acid ethanol solution, or 12.5% ​​sulfuric acid methanol solution. Stainless steel or nickel plate is used as cathode material. 3.4.2. Mechanical polishing: Rough polishing and fine polishing are carried out according to the mechanical polishing process. 4 Grain size test
4.1 The area method is to draw a Φ79.8mm circle (area of ​​5000mm2) or a rectangle with an area of ​​5000mm2 on the frosted glass of the microscope as the test point.
Wire cutting method can be adjusted to different positions by using the micrometer in the micrometer eyepiece, or one or several evenly drawn lines of equal length on the frosted glass of the microscope as test points.
4.2· Under the magnification of 100×～200×, observe the grain size and uniformity of distribution of the entire grinding surface, and record its significant features. For example, the uniformity of sintering hole distribution, whether there are cracks, etc. 4.3 Select five positions on any diagonal line of the sintered bad bar as test points, and the test positions are shown in the figure. For rods, five points should be evenly selected along the diameter direction as test points. 4.4 Different magnifications should be selected according to different materials. For the area method, the number of grains in the test area on the frosted glass of the dark box should be at least 50. For the wire cutting method, the number of grains cut by each test line shall not be less than 15, and the total number of grains cut by the test line group shall not be less than 50. 5 Grain size calculation
5.1·Area method
Calculate according to the following formula:wwW.bzxz.Net
Where:
Where: N
2, 3, 4, 5)
n: (i equals 1,
Number of grains per unit area of ​​the specimen, pieces/mm2, magnification;
Number of complete grains within the known area of ​​the ith test point; Number of grains intersected by the edge line at the ith test point; Average number of grains within a known area of ​​five test points; Number of grains within a known area of ​​the ith test point; K——Ratio of the square of the magnification to the test area. (1)
5.2 Wire cutting method
The test line passes through three grain boundaries. At the intersection, the test line end is calculated as 1/2 of the grain according to 11/25.2.1; when passing through the tangent point of two grains, it is calculated as 1 grain; when the shape of the grain is irregular, the test line cuts the same crystal powder twice, it is still calculated as one grain.
5.2.2 Calculation:
Where: 1:
Where: 1
2, 3, 4, 5)
i=1,
Average intercept of grains, mm;
Total length of test line group, mm,
Z;———Total number of grains cut by the i-th test line group; 4L2
B——Average number of grains cut by the test line group at five test points. 20
GB4197-84
Appendix A
(Supplement)
A.1 When CVWhen the value of the actual grain size and the coefficient of deviation CV can be reported, the actual grain size value and the coefficient of deviation CV value can be reported. A.2
Additional remarks:
This standard is proposed by the Standardization Institute of the Ministry of Electronics Industry. This standard is initiated by Factory 744.
The main drafter of this standard is Niu Shangmei.
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